1. Field of the Invention
The present invention relates to a manufacturing method for devices to be fabricated on a substrate, and a dicing method. More particularly, the present invention is a manufacturing method including a dicing process in which devices are cut off after the surfaces of the devices are protected with a protective film, and a dicing method.
2. Description of the Related Art
For example, manufacturing processes required for manufacturing multiple devices, which are fabricated on a substrate, for example, semiconductor devices or micro-electromechanical system (MEMS) devices include a dicing process in which the devices are separated. For example, some MEMS devices have a microscopic hole, channel, or a movable part. These devices are fragile due to low mechanical strength and may have flawed surfaces. Consequently, even in the dicing process, the devices may be broken due to vibration from cutting with a dicing saw. Moreover, the faces of the devices may be damaged by fine powder produced during cutting. Therefore, a dicing process has been proposed in which the faces of the devices are protected prior to dicing.
Japanese Unexamined Patent Publication No. 2000-349416 discloses a method in which, for example, after a thermal peel-apart adhesive tape is attached to the face of a semiconductor substrate, in which numerous MEMS devices are fabricated, in order to protect the face of the semiconductor substrate, dicing is performed and after the completion of the dicing, the thermal peel-apart adhesive tape is heated in order to sufficiently reduce adhesive strength, and then peeled off. However, when the face of a substrate is protected with an adhesive tape, if a movable member is fabricated on the face of the substrate, unless the adhesive tape is peeled off uniformly, the movable member may be adversely affected.
Japanese Unexamined Patent Publication No. 10-239346 discloses a method in which: after a semiconductor substrate in which numerous devices each including a movable part and a void are fabricated, is immersed in a resist solution in order to protect the face of the semiconductor substrate, with the resist cured, dicing is performed, and after dicing, the resist on the face of the substrate is removed using a resist peeling agent.
Japanese Unexamined Patent Publication No. 11-160570 discloses a method in which: when dicing is performed in order to dissociate numerous optical couplers which are fabricated on a substrate and each of which includes a dielectric block, a photo-resist is applied in advance to the light incidence surface or light reflecting surface of each dielectric block in order to form a protective film, and after dicing, the protective film is removed using a resist remover.
Problems using a resist as a protective film will be described with reference to FIG. 11 and FIG. 12. FIG. 11 shows a state prior to dicing of a semiconductor substrate placed on a dicing chuck. A semiconductor substrate 51 in which, for example, numerous through holes 52 that are examples of a microscopic structure are formed, has a dicing tape 54 attached to the back thereof, and is thus placed and immobilized on a dicing chuck 55. The face of the semiconductor substrate 51 is covered and protected with a photo-resist 53 of, for example, model AZ-P4210.
In a dicing process, semiconductor substrate 51 is diced together with photo-resist 53 using a dicing saw while water is sprayed on a cutting position. Thereafter, the photo-resist 53 is dissolved with a solvent and thus removed.
FIG. 12 shows a state in which devices are dissociated by grooves 56 formed by performing dicing and photo-resist 53 is removed. Photo-resist 53 covering semiconductor substrate 51 is dissolved by the solvent and removed. However, photo-resist 53 is not removed from part of the microscopic structures into which the solvent is hard to be absorbed. This poses a problem in that a residue 57 of the resist is left. Moreover, the residue of the resist may be left on the back of the semiconductor substrate.
An art in which a resist is not adopted as a protective agent has been unveiled. Japanese Unexamined Patent Publication No. 2001-44143 discloses a method in which: liquefied carbon dioxide is sprayed on a substrate so that dry ice will form on the substrate; in this state, dicing is performed while microparticles of dry ice are sprayed; and after dicing, while a stationary stage is cooled to room temperature, the microparticles of dry ice are further sprayed in order to remove shavings and the dry ice layer. However, when the dry ice is used, a dicing machine and a semiconductor substrate in which devices are fabricated have to be kept at a very low temperature. Moreover, since the semiconductor substrate is alternately brought to room temperature and a very low temperature, the devices may be adversely affected.
Japanese Unexamined Patent Publication No. 59-92356 discloses a method in which a thermally dissoluble polymeric resin, in other words, a resin that is a polymer which is dissolved into monomers when heated is used as a reinforcement resin for the surface of a semiconductor substrate. The reinforcement resin is fully decomposed and removed with heat dissipated during die bonding. However, heating must be used for removal of the thermally dissoluble polymeric resin. Furthermore, Japanese Unexamined Patent Publication No. 59-92356 has not discussed the issue of remaining fine powder produced during cutting.